DCDIAG /TEST:DNS fails with errors regarding root hint servers

I recently resolved an ongoing DNS issue where the Active Directory Integrated DNS was loaded in both the Domain and the DomainDNSZones partition of AD – this is a separate issue and should be resolved differently. My problem when I tried to verify that the fixed DNS setup had propogated around my domain controllers, DC01 and DC02. DC01 kept failing "DCDIAG /TEST:DNS" with errors regarding the root hint servers. Googling about it was clear that a lot of people were suffering the same issue, but no article I read had correctly identified the solution.

TEST: Dynamic update (Dyn)
Warning: Dynamic update is enabled on the zone but not secure
DOMAIN.com.

Summary of test results for DNS servers used by the above domain contro
llers:

DNS server: 128.63.2.53 (h.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 128.63.2.53

DNS server: 128.8.10.90 (d.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 128.8.10.90

DNS server: 192.112.36.4 (g.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.112.36.4

DNS server: 192.203.230.10 (e.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.203.230.10

DNS server: 192.228.79.201 (b.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.228.79.201

DNS server: 192.33.4.12 (c.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.33.4.12

DNS server: 192.36.148.17 (i.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.36.148.17

DNS server: 192.5.5.241 (f.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.5.5.241

DNS server: 192.58.128.30 (j.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 192.58.128.30

DNS server: 193.0.14.129 (k.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 193.0.14.129

DNS server: 198.41.0.4 (a.root-servers.net.)
1 test failure on this DNS server
This is not a valid DNS server. PTR record query for the 1.0.0.12
7.in-addr.arpa. failed on the DNS server 198.41.0.4

It looks pretty horrific – DNS is failing at a basic level! It turns out that the actual issue is an old version of DCDIAG.EXE. After several hours and a lot of head scratching I checked the versions of the DCDIAG.EXE (normally c:\Program Files\Support Tools\dcdiag.exe) and "Lo! And Behold!" the version was different. I downloaded the Windows Server 2003 Support Tools R2, uninstalled the old version (v5.2.3790.1800) and installed the new one (v5.2.3790.3959).